Gas liquefaction apparatus

ABSTRACT

A gas liquefaction apparatus includes a spraying tank, a pump, a heater, a separating member, a heat-releasing member, a flow control assembly and a liquid tank. The spraying tank includes a chamber, a gas inlet and a mixture outlet. The gas inlet and the mixture outlet are in communication with the chamber. A plurality of nozzles is installed in the chamber. The pump is connected to the mixture outlet. The heater is connected to the pump. The separating member includes a container and a heating device. The container comprises a mixture inlet and a gas outlet. The mixture inlet is connected to the heater. The container is equipped with the heating device. The heat-releasing member is connected to the gas outlet of the container. The flow control assembly is connected to the heat-releasing member. The liquid tank is connected to the flow control assembly.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a gas liquefaction apparatus and, more particularly, to a gas liquefaction apparatus with reduced energy consumption.

2. Description of the Related Art

Liquefied natural gas (LNG) or certain industrial gases (such as NH₃ or CO₂) are extremely unstable and require large storage spaces when they are in a gaseous state. These substances must be converted into a liquid state for safe storage and transportation.

As an example, FIG. 1 shows a conventional gas liquefaction apparatus 9 consisting of a compressor 91, a cooler 92 and a turbine 93 which are connected in series via pipes. As an example of carbon dioxide (CO₂), the gaseous carbon dioxide at a normal temperature and a normal pressure (the temperature is approximately 300 K, the pressure is approximately 1 atm) is guided into the compressor 91 so that the carbon dioxide is converted into gaseous carbon dioxide containing high temperature/high pressure CO_(2(g)) (the temperature is approximately 800 K, the pressure is approximately 20 atm). The gaseous carbon dioxide at the high temperature and the high pressure then flows into the cooler 92. The cooler 92 cools the gaseous carbon dioxide under the same pressure. The cooled carbon dioxide flows through the turbine 93. The cooled carbon dioxide is expanded and the pressure thereof is decreased as it flows through the turbine 93. Finally, gaseous carbon dioxide having low temperature/low pressure CO₂₍₁₎ is outputted from the turbine 93 for storage and future use.

However, it takes a significant amount of energy for the compressor 91 to compress gaseous substance from a normal temperature/normal pressure state into a high temperature/high pressure state since the gaseous substance has larger bond strength. In this regard, the gas liquefaction apparatus 9 is not efficient and economic, making it difficult to achieve energy saving as required in modern society. In light of this, it is necessary to improve the gas liquefaction apparatus 9.

SUMMARY OF THE INVENTION

It is therefore the objective of this invention to provide a gas liquefaction apparatus which mixes a low temperature/normal pressure substance with an absorbent by way of spraying, so as to produce a mixture that can be easily heated to a critical state for energy saving.

In one embodiment of the invention, a gas liquefaction apparatus includes a spraying tank, a pump, a heater, a separating member, a heat-releasing member, a flow control assembly and a liquid tank. The spraying tank includes a chamber, a gas inlet and a mixture outlet. The gas inlet and the mixture outlet are in communication with the chamber. A plurality of nozzles is installed in the chamber. The pump is connected to the mixture outlet. The heater is connected to the pump. The separating member includes a container and a heating device. The container comprises a mixture inlet and a gas outlet. The mixture inlet is connected to the heater. The container is equipped with the heating device. The heat-releasing member is connected to the gas outlet of the container. The flow control assembly is connected to the heat-releasing member. The liquid tank is connected to the flow control assembly.

In a preferred form shown, the heater is connected to the heat-releasing member.

In the preferred form shown, the flow control assembly further comprises a control valve and a flow-limiting valve. The control valve is connected between the heat-releasing member and the flow-limiting valve. The flow-limiting valve is connected to the liquid tank.

In the preferred form shown, the spraying tank comprises an injection hole. The container further comprises a backflow inlet connected to the injection hole via a pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 shows a block diagram of a conventional gas liquefaction apparatus.

FIG. 2 shows a structural diagram of a gas liquefaction apparatus according to a preferred embodiment of the invention.

In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “third”, “fourth”, “inner”, “outer” “top”, “bottom”, “front”, “rear” and similar terms are used hereinafter, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings, and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

The term “normal temperature” referred hereinafter represents the temperature of 300K, as it can be understood by one having ordinary skill in the art. The term “high temperature” referred hereinafter represents a temperature higher than the normal temperature, and the term “low temperature” represents a temperature lower than the normal temperature.

The term “normal pressure” referred hereinafter represents a pressure of 1 atm, as it can be understood by one having ordinary skill in the art. The term “high pressure” referred hereinafter represents a pressure larger than the normal pressure.

Referring to FIG. 2, a gas liquefaction apparatus is disclosed according to a preferred embodiment of the invention. The gas liquefaction apparatus includes a spraying tank 1, a pump 2, a heater 3, a separating member 4, a heat-releasing member 5, a flow control assembly 6 and a liquid tank 7. The pump 2 is connected to the spraying tank 1 and the heater 3. The separating member 4 is connected to the heater 3 and the heat-releasing member 5. The flow control assembly 6 is connected to the heat-releasing member 5 and the liquid tank 7.

The spraying tank 1 includes a chamber 11 receiving an absorbent L. The chamber 11 includes a plurality of nozzles 12 that sprays the absorbent L into the chamber 11 to efficiently mix the absorbent with incoming gas. The absorbent L and the gas may be mixed together to produce a binary solution. In the embodiment, the spraying tank 1 further includes a gas inlet 13 and a mixture outlet 14. Both the gas inlet 13 and the mixture outlet 14 are in communication with the chamber 11. The low temperature/normal pressure gas that is to be liquefied (such as NGL, NH₃ or CO₂, which is called “first gaseous substance” hereinafter) may be guided into the spraying tank 1 through the gas inlet 13. The first gaseous substance is sprayed into the absorbent L by the nozzles 12 in order to mix the first gaseous substance with the absorbent L. The mixed substance sinks down the chamber 11. As such, the first gaseous substance is able to rapidly mix with absorbent L into a low temperature/normal pressure mixture (which is called “first mixture” hereinafter) under the spraying performed by the nozzles 12. The first mixture is then guided out of the spraying tank 1 via the mixture outlet 14. The spraying tank 1 may further comprise an injection hole 15 in communication with the chamber 11.

The pump 2 is connected to the spraying tank 1 to pressurize the first mixture, so as to obtain a mixture with a low temperature and a high pressure (which is called “second mixture” hereinafter). In other words, the pump 2 simply increases the pressure of the first mixture so that the temperature of the first mixture is maintained. It is noted that, since the first mixture is pressurized in a hydraulic manner, a relatively smaller amount of energy is consumed as compared to the traditional pneumatic pressurization. In this embodiment, the pump 2 is connected to the mixture outlet 14 of the spraying tank 1.

The heater 3 is adapted to heat the second mixture to a critical point, so as to obtain a mixture with high temperature/high pressure (which is called “final mixture M” hereinafter).

The separating member 4 includes a container 41 and a heating device 42. The container 41 comprises a compartment 411. The container 41 is equipped with the heating device 42 that is adapted to heat the content in the container 41. In this embodiment, the heating device 42 may be installed in the compartment 411. Thus, when the final mixture M flows into the compartment 411, the heating device 42 is able to heat the final mixture M. As such, high temperature/high pressure gas is produced from the final mixture M (which is called “second gaseous substance” hereinafter) based on different boiling points. The separating member 4 further includes a mixture inlet 43 and a gas outlet 44. Both the mixture inlet 43 and the gas outlet 44 are in communication with the compartment 411. The mixture inlet 43 is connected to the heater 3 to allow the final mixture M to flow into the compartment 411. The container 41 may further include a backflow inlet 45 in communication with the compartment 411. The backflow inlet 45 may be connected to the injection hole 15 via a pipe. In this arrangement, the final mixture M in the compartment 411 may flow back to the chamber 11 via the backflow inlet 45 and the injection hole 15.

The heat-releasing member 5 is connected to the separating member 4 to release the heat Q from the second gaseous substance. The second gaseous substance turns into a third gaseous substance after the second gaseous substance cools down. Specifically, the heat-releasing member 5 is connected to the gas outlet 44. In addition, the heat-releasing member 5 may also be connected to the heater 3 to guide the heat Q of the second gaseous substance into the heater 3, allowing the heater 3 to heat the second mixture using the heat Q. In this manner, the heater 3 and the heat-releasing member 5 may jointly construct a heat-exchanging assembly capable of reducing the energy consumption of the heater 3.

The flow control assembly 6 is adapted to maintain the third gaseous substance in a certain flow. The flow control assembly 6 is also able to reduce the temperature and pressure of the third gaseous substance, turning the third gaseous substance into a liquid substance having low temperature/low pressure. Specifically, the flow control assembly 6 includes a control valve 61 and a flow-limiting valve 62. The control valve 61 is connected between the heat-releasing member 5 and the flow-limiting valve 62. Therefore, the third gaseous substance flows from the heat-releasing member 5 to the control valve 61 and the flow-limiting valve 62 in order. The control valve 61 is adapted to control the flow of the third gaseous substance to ensure the safety of the liquefaction process. The flow-limiting valve 62 may be adapted to perform the isenthalpic process to reduce the temperature and pressure of the third gaseous substance, turning the third gaseous substance into a liquid substance having low temperature/low pressure.

The liquid tank 7 is adapted to store the low temperature/low pressure liquid substance. In the embodiment, the liquid tank 7 is connected to the flow-limiting valve 62 for receiving the liquid substance from the flow-limiting valve 62.

Referring to FIG. 2 again, liquefied natural gas is exemplarily used to illustrate the operation of the gas liquefaction apparatus. First, when the absorbent L is injected into the chamber 11, the low temperature/normal pressure LNG (LNG_((g)), the first gaseous substance) is guided into the spraying tank 1 via the gas inlet 13. The first gaseous substance LNG_((g)) is then mixed with absorbent L into the first mixture under the spraying operation performed by nozzles 12. The first mixture flows through the pump 2 via the mixture outlet 14 for pressurization. The first mixture then flows through the heater 3 for heating purpose. Thus, the first mixture is converted into the second mixture. The second mixture is then converted into the final mixture M which flows into the compartment 411 via the mixture inlet 43.

Next, the heating device 42 heats the final mixture M to produce the high temperature/high pressure LNG_((g)) (the second gaseous substance).

The high temperature/high pressure LNG_((g)) is guided to the heat-releasing member 5 via the gas outlet 44 in order to release the heat Q from the high temperature/high pressure LNG_((g)). Upon release of the heat Q from the high temperature/high pressure LNG_((g)), the high temperature/high pressure LNG_((g)) cools down as high pressure LNG_((g)) (the third gaseous substance). The third gaseous substance flows towards the flow control assembly 6. The temperature and pressure of the third gaseous substance are reduced under the isenthalpic process in order to produce the low temperature/low pressure liquid substance. Finally, the low temperature/low pressure liquid substance flows into the liquid tank 7 for storage and future transportation.

In conclusion, in the gas liquefaction apparatus described above, the first gaseous substance that is to be liquefied is mixed with the absorbent L by way of spraying, so as to produce the low temperature/normal pressure mixture (in the liquid form). Since the low temperature/normal pressure mixture has smaller bond strength than the gaseous substance, the low temperature/normal pressure mixture can be heated to the critical state using a lesser amount of energy. Furthermore, it also takes a lesser amount of energy for the heating device 42 to heat the high temperature/high pressure gaseous substance (the second gaseous substance). Based on this, the gas liquefaction apparatus in the above embodiment allows the gaseous substance to be efficiently converted into liquid substance for storage and transportation, achieving energy saving.

Although the invention has been described in detail with reference to its presently preferable embodiments, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims. 

What is claimed is:
 1. A gas liquefaction apparatus comprising: a spraying tank comprising a chamber, a gas inlet and a mixture outlet, wherein the gas inlet and the mixture outlet are in communication with the chamber, and wherein a plurality of nozzles is installed in the chamber; a pump connected to the mixture outlet; a heater connected to the pump; a separating member comprising a container and a heating device, wherein the container comprises a mixture inlet and a gas outlet, wherein the mixture inlet is connected to the heater, and wherein the container is equipped with the heating device; a heat-releasing member connected to the gas outlet of the container; a flow control assembly connected to the heat-releasing member; and a liquid tank connected to the flow control assembly.
 2. The gas liquefaction apparatus as claimed in claim 1, wherein the heater is connected to the heat-releasing member.
 3. The gas liquefaction apparatus as claimed in claim 1, wherein the flow control assembly further comprises a control valve and a flow-limiting valve, wherein the control valve is connected between the heat-releasing member and the flow-limiting valve, and wherein the flow-limiting valve is connected to the liquid tank.
 4. The gas liquefaction apparatus as claimed in claim 1, wherein the spraying tank further comprises an injection hole, and wherein the container further comprises a backflow inlet connected to the injection hole via a pipe. 